The invention relates to cargo delivery vehicles. More particularly, the invention relates to cargo delivery vehicles having multiple tiers of cargo storage which can be easily accessed for loading purposes through the rear doors, and can be unloaded through side access doors without requiring total bodily entry into the delivery vehicle in order to retrieve any portion of the cargo.
It is desirable to store and transport a wide variety of cargo in vehicles having multiple storage tiers so that the most efficient use of the interior space in the vehicle can be made. In many distribution industries, single-tier delivery vehicles suffer from several disadvantages resulting in the inability to utilize the full vertical capacity of the cargo area. One such disadvantage is that stacking cargo to excessive heights introduces potential payload instability. A second disadvantage is that excessive stacking often results in cumbersome access for manual unloading. A third disadvantage of excessive cargo stacking is that upper cargo may crush lower cargo. The structure of an upper tier cargo platform acts as a shelf by keeping the weight of the upper cargo from damaging crushable lower cargo, thus allowing a delivery vehicle to minimize its wheelbase and turning radius by carrying an increased payload capacity in weight per unit of area.
It is also desirable in many distribution applications to utilize a delivery vehicle engineered to provide the structural versatility to both (1) accept palletized cargo through rear doors, as from a warehouse dock, and (2) permit total and random side access to cargo at multiple delivery stops without the inefficiencies or hazards associated with unloading personnel being required to enter the vehicle in order to effect total cargo retrieval.
Typically, the features of rear loading and random-access side unloading are mutually exclusive in the known art of enclosed delivery vehicle construction. Some delivery vehicles in the food service industry provide rear loading with only limited side access, thus requiring total bodily entry into the vehicle in order to fully unload. This arrangement may achieve advantageous loading capabilities, yet suffer from unloading inefficiencies. Conversely, delivery vehicles common to the beverage distribution industry often permit total exterior access to the cargo areas through multiple side doors for unloading, but structurally and logistically prohibit rear loading.
It is still further desirable to provide an elevating means for raising and lowering segmented upper tier cargo platforms such that both an upper and lower tier may be loaded or unloaded from the lower level. Total exterior access to all cargo may be preferably achieved via side doors permitting access to multiple sections of the lower level. The elevating means may then provide the capability to lower upper tier cargo to the side-accessible lower level for retrieval.
Multi-tier storage of cargo is well known in the art. For example, it is known to provide upper and lower fixed storage platforms in a multi-tier cargo storage vehicle, as described in U.S. Pat. No. 4,139,109 issued Feb. 13, 1989 to Murphy. A single rear elevator apparatus used to vertically transfer cargo between fixed tiers, as disclosed in the patent to Murphy, possesses the disadvantage that a fixed upper tier cargo platform may prohibit loading personnel from entering the rear of the vehicle to facilitate the forward conveyance of cargo through the interior of the vehicle. Likewise, cargo vehicles with fixed tiers can not provide random access to all tiers of cargo through side access doors positioned at the lowermost tier.
A variety of specialized interior elevator arrangements have been developed to overcome the disadvantages of exterior lift mechanisms and fixed tiers for multi-tier storage. For example, U.S. Pat. No. 2,832,636 issued Apr. 29, 1958 to Black, discloses the use of a single interior elevator platform extending the length of the cargo storage space, which enables the transportation of cargo in two tiers. Segmented platforms formed by multiple adjoining elevators have also been proposed, such as in U.S. Pat. No. 4,701,086 issued Oct. 20, 1987 to Thorndyke. These segmented platforms provide two-tier storage in certain segments and single-tier storage in other segments where tall cargo is to be stored. A similar segmented platform lift apparatus in a multi-tier double drop trailer has been disclosed in U.S. Pat. No. 5,092,721 issued Mar. 3, 1992 to Prince.
But these vehicles with interior elevators are structurally limited to receiving and delivering cargo through rear doors only. As in the arrangement shown by Murphy, the forward cargo is inaccessible while the aft cargo is in place. Such an arrangement may provide a spatially efficient means of transporting cargo between destinations; however, they may be ill suited for adaptation to delivery applications in which cargo retrieval efficiency is a primary concern. Modern distribution systems frequently require the transportation of cargo from a warehouse to multiple delivery stops where unloading efficiency can be greatly enhanced by direct and random access to the entire lower tier through a series of side doors and where an elevating means can also position upper tier cargo platforms at the lower tier level.
A further disadvantage of the vehicles disclosed by Black, Thomdyke, and Prince is that they have elevating cargo platforms that extend transversely the full width of the vehicle' interior. Although full-width elevating platforms can thereby accept cargo up to eight feet wide, it may be more desirable for cargo portions to be longitudinally divided and independently accessible such that cargo placed within a lower tier cargo portion must reside within the average workman's arm's reach, so that his body may remain substantially outside of the delivery vehicle. Accordingly, half-width elevating platforms may reduce the workman's susceptibility to fatigue and injury, since he need not bodily enter the vehicle to load or unload cargo.
In conventional enclosed delivery vehicles having single-tier or multi-tier storage, the floor is typically required to bear the weight of the cargo and transfer those forces longitudinally through either floor or side wall members to the vehicle's axles. The requirement for numerous, closely spaced structural members in the sidewalls may limit the availability of sizable doors for cargo access from the side of the vehicle. Some conventional vehicles offer limited side access through doors penetrating the sidewalls, but such doors are necessarily limited because of the structural compromises they create. Therefore, it is desirable to minimize the load-bearing requirements of the sidewalls of the delivery vehicle in order to afford virtually continuous side access to the cargo.
Moreover, in the construction of enclosed delivery vehicles, the load-bearing floor is typically required to be quite thick for adequate structural support, thereby decreasing the interior space for storage. Therefore, it is also desirable to minimize the load-bearing requirements of the floor of the delivery vehicle in order to maximize interior storage space, especially space located in the ergonomically advantageous lower zone of the trailer.
Accordingly, it is an object of the present invention to provide multi-tier cargo storage in a delivery vehicle.
It is a further object of the invention to provide an enclosed, multi-tier delivery vehicle, which can be loaded completely through rear doors of the vehicle and unloaded completely through side doors of the vehicle.
A still further object of the invention is to provide an enclosed, multi-tier delivery vehicle, which permits direct and simultaneous exterior access to cargo located at the lowermost tier.
A still further object of the invention is to provide an enclosed, multi-tier delivery vehicle with multiple side access ports through which the entirety of the cargo can be manually unloaded without requiring unloading personnel to bodily enter the vehicle.
A still further object of the invention is to provide an enclosed, multi-tier delivery vehicle in which all tiers can be loaded and unloaded at the lowermost tier.
A still further object of the invention is to provide an enclosed, multi-tier delivery vehicle in which the cargo storage area is longitudinally bisected in order that cargo portions may remain within arm's reach of a side wall access door.
A still further object of the invention is to provide an enclosed, multi-tier delivery vehicle in which the load-bearing requirements placed on the side walls and floor are substantially reduced, permitting greater side access to cargo, and minimizing the vertical height of the floor.